There has been a storage for a virtualized environment, or so-called a virtualized storage device serving as a storage system capable of realizing a memory device with a volume configuration and a memory capacity which are freely designed without being bound by physical factors of a memory device such as a volume configuration and a memory capacity. When the virtualized storage device offers a volume to a server, processing to format the volume is executed. In the format processing, zero data is written in a corresponding physical memory area in the storage, for example.
Related background art includes a technique which is configured to control execution of zero-initialization processing on a memory area in a storage unit to undergo zero-initialization, the storage unit being specified by assignment information containing as assignment status of the memory area in the storage unit, depending on performance information on the storage unit. Meanwhile, there is a technique configured such that, when there is an instruction for formatting and the like that involves an externally coupled volume, a controller in a main storage converts commands for that instruction into formatting instructions or area release instructions targeted at an allocation-on-use (AOU) volume in an external storage. Moreover, there is also a technique configured such that, when data is recorded in a virgin cluster on a data track, null data is written in a write buffer for one cluster, then write data is written in a location corresponding to an allocation block to record the write data, and the data for the one cluster written in the write buffer is recorded in a cluster on the data track. These techniques of the background art are disclosed in Japanese Laid-open Patent Publication Nos. 2015-143945, 2010-55557, and 8-147110.